Cerebral blood flow volume measurements of the carotid artery and ipsilateral branches using two-dimensional phase-contrast magnetic resonance angiography

The optimal velocity encoding of phase-contrast magnetic resonance angiography （PC MRA） in measuring cerebral blood flow volume （BFV） ranges from 60 to 80 cm/s. To verify the accuracy of two-dimensional （2D） PC MRA, the present study localized the region of interest at blood vessels of the neck using PC MRA based on three-dimensional time-of-flight sequences, and the velocity encoding was set to 80 cm/s. Results of the measurements showed that the error rate was 7.0±6.0% in the estimation of BFV in the internal carotid artery, the external carotid artery and the ipsilateral common carotid artery. There was no significant difference, and a significant correlation in BFV between internal carotid artery ＋ external carotid artery and ipsilateral common carotid artery. In addition, the BFV of the common carotid artery was correlated with that of the ipsilateral internal carotid artery. The main error was attributed to the external carotid artery and its branches. Therefore, after selecting the appropriate scanning parameters and protocols, 2D PC MRA is more accurate in the determination of BFV in the carotid arteries.

Magnetic resonance angiography in the mana-gement of patients with portal hypertension

BACKGROUND: In recent years, MR techniques have been widely used for displaying hepatic vessels and measuring its hemodynamics, especially in the management of the patients with portal hypertension. The aim of this study was to eva- luate the role of magnetic resonance angiography (MRA) in the treatment of patients with portal hypertension. METHODS: A series of 38 patients with portal hypertension and 12 control patients were enrolled in this study. Three dimensional dynamic contrast-enhanced (3D-DCE) MRA and two dimensional phase-contrast (2D-PC) MR were used for the study of portal venous anatomy and its hemo- dynamics, which were compared with those of indirect portal-venography (IPVG) and doppler ultrasonography (DUS). RESULTS: The anatomical imaging of the portal venous system could be displayed clearly in 3D-DCE MRA and the imaging quality of MRA was better than that of IPVG. The hemodynamic information from 2D-PC MR was closely re- lated to that from DUS. CONCLUSIONS: As a non-invasive technique, MRA can display the anatomy of the portal venous system clearly and measure its hemodynamics exactly. It is very useful and can be applied if necessary in the management of patients with portal hypertension.

Celiomesenteric trunk demonstrated by 3-dimensional contrast-enhanced magnetic resonance angiography

Celiomesenteric trunk is a rare vascular anomaly, which has significant clinical implications. 3-di-mensional contrast-enhanced magnetic resonance angiography (3D CE MRA) is a new imaging modality, non-invasive , fast and easy to perform. We describe a patient with a common celiomesenteric trunk demonstrated by 3D CE MRA. METHODS: A 45-year-old man was subjected to 3D CE MRA before transarterial chemoembolization (TACE) for hepatocellular carcinoma. The examination was performed on a 1.5T MR imager with a body coil. The contrast medium was gadopentetate dimeglumine. Source images from the hepatic arterial phase acquisition were reconstructed into MRA images. Intra-arterial digital subtraction angiography (DSA) during TACE was carried out 3 days after 3D CE MRA. RESULTS:On 3D CE MRA, a common trunk of the celiac and superior mesenteric artery was clearly depicted. The origin and course of the hepatic, splenic and superior mesenteric arteries were also visualized. These findings were confirmed by intra-arterial DSA. CONCLUSIONS: Celiomesenteric trunk can be well delineated by 3D CE MRA. The image is correlated precisely with that from DSA.

Modified magnetic resonance angiography of the liver using sensitivity encoding in comparison with digital subtraction angiography and CT arterial portography

BACKGROUND: Over 355 patients have received ortho- topic liver transplantation ( OLT) at this hospital since 1993. Preoperative imaging studies of both hepatic vessels and parenchyma in these recipients bettered surgical plan- ning or even precluded the necessity of surgery. Here we report our preliminary results of modified magnetic reso- nance angiography ( MRA ) using sensitivity encoding ( SENSE) through comparative study with conventional digital subtraction angiography (DSA) and CT arterial por- tography (CTAP). METHODS: Sixteen patients with suspected liver diseases were included in the study. All of them received both dy- namic MRI of the liver using SENSE and digital DSA with CTAP within a two-week interval. The four-phase MRA was reconstructed from source images of the coronal dy- namic study. The arterial phase of the modified MRA was compared with DSA in the evaluation of hepatic arteries and the portal phase compared with CT portography recon- structed from source images of CTAP. In dynamic study of the liver, a fixed dose (20 ml) of contrast medium and scan timing were used. RESULTS: The main branches and variations of the hepatic arterial system were well shown on the modified MRA, al- though the marginal branches of hepatic arteries were of poor quality. The figures of portal veins on MRA were as clear as or superior to those of CTAP. In addition, the su- prarenal inferior vena cava (IVC) was well demonstrated on MRA and/or non contrast-enhanced coronal balanced fast-field echo (b-FFE) scan sequence in most cases. MRI detected most parenchymal lesions of the liver and hemo- dynamics of these lesions could be evaluated on source ima- ges of the modified MRA. MRI/MRA also serendipitously revealed several extrahepatic disease entities or variations that were not found on DSA/CTAP. CONCLUSIONS: The modified MRA using SENSE is a cost-effective modality of examination for the demonstra- tion of the whole hepatic vascular system. Combined with MRI, it has the potential as a one-stop imaging modality in the preoperative evaluation in fields such as OLT.

Three-dimensional time-of-flight magnetic resonance angiography combined with high resolution T2-weighted imaging in preoperative evaluation of microvascular decompression

BACKGROUND Neurovascular compression(NVC) is the main cause of primary trigeminal neuralgia(TN) and hemifacial spasm(HFS). Microvascular decompression(MVD) is an effective surgical method for the treatment of TN and HFS caused by NVC. The judgement of NVC is a critical step in the preoperative evaluation of MVD, which is related to the effect of MVD treatment. Magnetic resonance imaging(MRI) technology has been used to detect NVC prior to MVD for several years. Among many MRI sequences, three-dimensional time-of-flight magnetic resonance angiography(3D TOF MRA) is the most widely used. However, 3D TOF MRA has some shortcomings in detecting NVC. Therefore, 3D TOF MRA combined with high resolution T2-weighted imaging(HR T2WI) is considered to be a more effective method to detect NVC.AIM To determine the value of 3D TOF MRA combined with HR T2WI in the judgment of NVC, and thus to assess its value in the preoperative evaluation of MVD.METHODS Related studies published from inception to September 2022 based on PubMed, Embase, Web of Science, and the Cochrane Library were retrieved. Studies that investigated 3D TOF MRA combined with HR T2WI to judge NVC in patients with TN or HFS were included according to the inclusion criteria. Studies without complete data or not relevant to the research topics were excluded. The Quality Assessment of Diagnostic Accuracy Studies checklist was used to assess the quality of included studies. The publication bias of the included literature was examined by Deeks’ test. An exact binomial rendition of the bivariate mixed-effects regression model was used to synthesize data. Data analysis was performed using the MIDAS module of statistical software Stata 16.0. Two independent investigators extracted patient and study characteristics, and discrepancies were resolved by consensus. Individual and pooled sensitivities and specificities were calculated. The I_(2) statistic and Q test were used to test heterogeneity. The study was registered on the website of PROSERO(registration No. CRD42022357158).RESULTS Our search identified 595 articles, of which 12(including 855 patients) fulfilled the inclusion criteria. Bivariate analysis showed that the pooled sensitivity and specificity of 3D TOF MRA combined with HR T2WI for detecting NVC were 0.96 [95% confidence interval(CI): 0.92-0.98] and 0.92(95%CI: 0.74-0.98), respectively. The pooled positive likelihood ratio was 12.4(95%CI: 3.2-47.8), pooled negative likelihood ratio was 0.04(95%CI: 0.02-0.09), and pooled diagnostic odds ratio was 283(95%CI: 50-1620). The area under the receiver operating characteristic curve was 0.98(95%CI: 0.97-0.99). The studies showed no substantial heterogeneity(I2 = 0, Q = 0.001 P = 0.50).CONCLUSION Our results suggest that 3D TOF MRA combined with HR T2WI has excellent sensitivity and specificity for judging NVC in patients with TN or HFS. This method can be used as an effective tool for preoperative evaluation of MVD.

Fenestration of the anterior cerebral artery detected by magnetic resonance angiography

Background Fenestration of the proximal anterior cerebral artery （ACA） A1 segment is a rare anatomic variation. The purpose of the this study was to report the incidence of fenestration in the proximal segment of the anterior cerebral artery and to delineate its configurations on cranial MR angiography.Methods Magnetic resonance angiography （MRA） was performed in 762 patients using 1.5T imagers during the period July 2007 through September 2008. All images were obtained by the three-dimensional time-of-flight （3D TOF） technique Volume rendering （VR） images in the horizontal rotation view were displayed stereoscopically. The presence of fenestration in the proximal segment of the anterior cerebral artery was identified and evaluated retrospectively by MRA. Results Six patients （four men and two women, 15 to 63 years of age, median age 50 years） had proximal ACA fenestration. The appearance rate of ACA fenestration was 0.8% （6/762）. All 6 fenestrations were located at the A1 segment： three of them were with a slit-like shape and three were with a convex-lens-like shape, 5 of the right A1 segment, 1 of the left A1 segment.Conclusion Recognizing ACA fenestration is important to interpret cranial MR angiographys and helpful to make a plan for neurosurgical procedures or neurological intervention.

Diagnosis of systemic arterial diseases with whole-body 3D contrast-enhanced magnetic resonance angiography

Background With the development of magnetic resonance （MR） technologies, whole-body 3D contrastenhanced MR angiography （3D CE MRA） has become possible. The purpose of this study was to introduce and evaluate this technique in demonstration of various systemic arterial diseases. Methods Thirty-seven patients underwent whole-body 3D CE MRA using a 1.5T MR imager. The patients included were with clinically documented or suspected peripheral arterial occlusive disease （PAOD, n=19）, Takayasu arteritis （n=8）, polyarteritis nodosa （n=1）, Type B dissection （n=4） and thoracic and/or abdominal aneurysm （n=5）. Sixty-eight surface coil elements were employed to encompass the whole body. Four 3D CE MRA stations were acquired successively through automatic table moving. A total scan range of 188 cm, covering the arterial tree from carotid artery to trifurcation vessels, was acquired. Overall image quality of each arterial segment and venous overlay were assessed and rated. The depiction of various systemic arterial diseases was evaluated and compared with other imaging modalities if available, including digital subtraction angiography （DSA）, CT angiography, dedicated mono-station MRA. Results Whole-body 3D CE MRA was well tolerated by all patients. It yielded a detailed display of the arterial system with a short examination time. The image quality was considered diagnostic in 99.3% of the arterial segments. The remaining 0.7% of the arterial segments were considered non-diagnostic. In 7 of 19 patients with PAOD, whole-body MRA showed additional vascular narrowing apart from peripheral arterial disease. In 9 patients with vasculitis, whole-body MRA depicted luminal irregularity, narrowing or occlusion, aneurysm and collateral circulation involving multiple vascular segments. Whole-body MRA also clearly revealed the severity and extent of dissection and aortic aneurysm. In 20 cases the vascular pathologies demonstrated on whole body MRA were confirmed by other imaging investigations. Conclusions The whole-body MRA technique was non-invasive, quick and easy to perform. It was valuable for a comprehensive evaluation of vascular involvement of various systemic arterial diseases.

Magnetic resonance imaging and magnetic resonance angiography in severe crush syndrome with consideration of fasciotomy or amputation： a novel diagnostic tool

Three cases of severe crush syndrome after the Wenchuan earthquake in China are presented. The patients, 2 males and one female ranging in age from 18-45 years were studied via 1.5 T magnetic resonance imaging （MRI） and magnetic resonance angiography （MRA）. MRI examinations were performed more than twice on two patients within 60 days of the earthquake. All the patients had acute renal failure （ARF） with plasma myoglobin concentrations above 17 000 pg/L. The T2-weighted and short time inversion recovery （STIR） sequences revealed high intensity lesions in the affected muscles, and enhanced Tl-weighted images showed enhancement of partial affected muscles. MRA revealed no signs of arterial occlusion, artedostenosis, or filling defects of main arteries. All patients were managed medically with continuous venous-venous hemofiltration and other supportive care, and none required fasciotomy or amputation. Repeat MR studies showed that the high intensity lesions seen on the T2-weighted and STIR sequences resolved in parallel with improvement of laboratory studies and clinical course.

Quantitative analysis of cerebrovascular characteristics of Parkinson's disease treated with acupuncture based on magnetic resonance angiography

Background:Acupuncture has become an important alternative clinical treatment for Parkinson’s disease(PD),but its efficacy and the underlying mechanisms remain debatable.Using a newly developed magnetic resonance angiography(MRA)method that has higher sensitivity for smaller and distal vessels and a novel tool that can trace vessels and extract vascular features,the immediate effects of acupuncture on intracranial vessels and blood flow in patients with PD as well as correlations with clinical outcomes were quantitatively evaluated.Methods:Fifteen PD patients received acupuncture at the Dazhui and Fengchi acupoint positions.MRA was performed before and after 30 min of treatment.The cerebral blood flow(CBF)and the length,volume,diameter,and signal intensity of the intracranial internal carotid artery(ICA)and middle cerebral artery(MCA)were measured.The Unified Parkinson’s Disease Rating Scale partⅢ(UPDRS-Ⅲ)and Visual Analogue Scale(VAS)were used to evaluate the motor symptoms and the subjective feelings of discomfort.Results:Acupuncture significantly reduced UPDRS-Ⅲand VAS scores.No significant changes were noted in the overall CBF before and after treatment.However,there was a significant extension effect on the length of the intracranial ICA and MCA and the distal MCA,and a significant increase in the number of branches of the MCA was found.Although acupuncture tended to increase the total volume of the intracranial ICA and the volume of the MCA,no statistical significance was reached.The total intensity was not altered,but the intensity and diameter of the M1 segment were significantly increased,whereas the intensity of the MCA was decreased.A positive correlation between M1 intensity changes and UPDRS-Ⅲchanges was found.Conclusions:Angiographic evaluation suggested that acupuncture had a significant effect on intracranial blood vessels,which is one possible mechanism for acupuncture improving the motor symptoms of PD.

A free-breathing non-contrast-enhanced pulmonary magnetic resonance angiography at 3 Tesla

Background The breathhold contrast-enhanced three-dimensional magnetic resonance angiography （MRA） using Tl-weighted gradient-echo imaging sequence is the standard technique for MRA of the thorax. However, this technique is not desirable for certain patients with respiratory insufficiency, serious renal impairment, or allergy to contrast agents. The objective of this study was to optimize and evaluate a non-contrast-enhanced free-breathing pulmonary MRA protocol at 3 Tesla. Methods The time-of-flight protocol was based on a two-dimensional Tl-weighted turbo field echo sequence with slice-selective inversion recovery and magnetization transfer preparation together with respiratory navigator gating, cardiac gating, and parallel imaging. Optimal values for time of inversion delay, flip angle and slice thickness were experimentally determined and used for all subjects. Results Excellent pulmonary MRA images, in which the 7th order branches of pulmonary arteries could be reliably identified, were obtained in the 12 free-breathing healthy volunteers. TI of -300 ms provides the best suppression of background thoracic and cardiac muscles and effective inflow enhancement. With increasing flip angle, the pulmonary vessels gradually brightened and exhibited optimal contrast at 20°-30°. The 2 mm slice thickness and 0.5 mm slice overlap is suitable for visualization of the peripheral pulmonary vessel. Conclusions The MRA protocol at 3 Tesla may have clinical significance for pulmonary vascular imaging in patients who are not available for contrast-enhanced 3D MRA and CT angiography examination or are unable to sustain a long breath-hold.

Application of MAGnetic resonance imaging compilation in acute ischemic stroke

BACKGROUND Synthetic magnetic resonance imaging(MRI)MAGnetic resonance imaging compilation(MAGiC)is a new MRI technology.Conventional T1,T2,T2-fluidattenuated inversion recovery(FLAIR)contrast images,quantitative images of T1 and T2 mapping,and MAGiC phase sensitive inversion recovery(PSIR)Vessel cerebrovascular images can be obtained simultaneously through post-processing at the same time after completing a scan.In recent years,studies have reported that MAGiC can be applied to patients with acute ischemic stroke.We hypothesized that the synthetic MRI vascular screening scheme can evaluate the degree of cerebral artery stenosis in patients with acute ischemic stroke.AIM To explore the application value of vascular images obtained by synthetic MRI in diagnosing acute ischemic stroke.METHODS A total of 64 patients with acute ischemic stroke were selected and examined by MRI in the current retrospective cohort study.The scanning sequences included traditional T1,T2,and T2-FLAIR,three-dimensional time-of-flight magnetic resonance angiography(3D TOF MRA),diffusion-weighted imaging(DWI),and synthetic MRI.Conventional contrast images(T1,T2,and T2-FLAIR)and intracranial vessel images(MAGiC PSIR Vessel]were automatically reconstructed using synthetic MRI raw data.The contrast-to-noise ratio(CNR)values of traditional T1,T2,and T2-FLAIR images and MAGiC reconstructed T1,T2,and T2-FLAIR images in DWI diffusion restriction areas were measured and compared.MAGiC PSIR Vessel and TOF MRA images were used to measure and calculate the stenosis degree of bilateral middle cerebral artery stenosis areas.The consistency of MAGiC PSIR Vessel and TOF MRA in displaying the degree of vascular stenosis with computed tomography angiography(CTA)was compared.RESULTS Among the 64 patients with acute ischemic stroke,79 vascular stenosis areas showed that the correlation between MAGiC PSIR Vessel and CTA(r=0.90,P<0.01)was higher than that between TOF MRA and CTA(r=0.84,P<0.01).With a degree of vascular stenosis>50%assessed by CTA as a reference,the area under the receiver operating characteristic(ROC)curve of MAGiC PSIR Vessel[area under the curve(AUC)=0.906,P<0.01]was higher than that of TOF MRA(AUC=0.790,P<0.01).Among the 64 patients with acute ischemic stroke,39 were scanned for traditional T1,T2,and T2-FLAIR images and MAGiC images simultaneously,and CNR values in DWI diffusion restriction areas were measured,which were:Traditional T2=21.2,traditional T1=-6.7,and traditional T2-FLAIR=11.9;and MAGiC T2=7.1,MAGiC T1=-3.9,and MAGiC T2-FLAIR=4.5.CONCLUSION The synthetic MRI vascular screening scheme for patients with acute ischemic stroke can accurately evaluate the degree of bilateral middle cerebral artery stenosis,which is of great significance to early thrombolytic interventional therapy and improving patients’quality of life.

Oleic Acid (OA), A Potential Dual Contrast Agent for Postmortem MR Angiography (PMMRA): A Pilot Study

Summary:Choosing proper perfusates as contrast agents is an important aspect for postmortem magnetic resonance angiography(PMMRA).However,in this emerging field,the number of suitable kinds of liquid is still very limited.The objective of this research is to compare MR images of oleic acid(OA)with paraffin oil(PO)in vitro and in ex situ animal hearts,in order to evaluate the feasibility to use OA as a novel contrast agent for PMMRA.In vitro,OA,PO and water(control)were introduced into three tubes separately and T,weighted-spin echo(Tw SE)and T2w-SE images were acquired on a 1.5T MR scanner.In the second experiment,0A and PO were injected into left coronary artery(LCA)and left ventricle(LV)of ex situ bovine hearts and their Tw-SE,Tzw-SE,Tw-multipoint Dixon(Tjw-mDixon)and 3DT2w-mDixon images were acquired.The overall results indicate that OA may have a potential to be used as a dual(T and T2 based)contrast agent for PMMRA when proper sequence parameters are utilized.However,as the pilot study was based on limited number of animal hearts,more researches using OA in cadavers are needed to validate our findings.

Pulmonary Sequestration: Three Dimensional Dynamic Contrast-enhanced MR Angiography and MRI

In order to evaluate the diagnostic value of three dimentional contrast enhanced MR angiography and MRI for pulmonary sequestration, 5 patients with pulmonary sequestration underwent 3D fast imaging by steady state precession (FISP) with a contrast medium and breath holding following chest radiography, CT and MR scans. The reconstructed MR angiography was performed using maximum intensity projection (MIP) and multiplanar reconstruction (MPR) techniques. It was found that the chest radiography showed pulmonary sequestration as a persistent area of opacity in the posterior basal segment of the left lower lobe, which was close to mediastinum in 2 cases and close to diaphragma in 3 cases. CT revealed a soft issue mass beyond descending aorta and lobar emphysema around the pulmonary sequestration. And the supplying vessel was documented in 2 cases on enhanced CT. MRI demonstrated a hyperintensity mass with respect to normal lung parenchyma on T1WI and T2WI, and the origin of the supplying vessel in 3 cases. The reconstructed CE MRA using MIP or MRP techniques clearly showed the supplying vessel and its course, branches as well as draining vessels. It was concluded that 3D CE MRA of demonstrating the supplying and draining vessels to pulmonary sequestration, together with plain MRI, can provide a diagnosis and aid in surgical planning without the need for DSA.

Characteristics of vascular lesions in patients with posterior circulation infarction according to age and region of infarct

Patients with posterior circulation infarction underwent CT angiography and magnetic resonance angiography. Intracranial and extracranial vasculopathy was evaluated according to age group and location of stroke. Patients aged 〉 60 years and 〈 60 years had similar rates of vertebral artery dominance and vertebrobasilar artery developmental or origin anomalies. Vertebrobasilar artery stenosis or occlusion and tortuosity occurred more frequently in patients aged 〉 60 years than 〈 60 years. The rates of vertebrobasilar artery anomalies and tortuosity were high in patients with posterior circulation infarction. Vertebrobasilar artery tortuosity occurred more frequently in patients aged 〉 60 years, whereas vertebrobasilar artery developmental anomalies occurred with similar frequency in patients aged 〈 60 years and 〉 60 years. Patients with infarction of the brainstem or cerebellum were more ~ikely to have vertebral artery stenosis or occlusion, basi^ar artery stenosis or occlusion, vertebral artery dominance or tortuosity, and basilar artery tortuosity, and patients with infarction of the thalamus, medial temporal, or occipital lobes were more likely to have stenosis or occlusion of the vertebral or basilar arteries. Vertebrobasilar artery tortuosity, vertebral artery dominance （hypoplasia）, and congenital variations of the vertebrobasilar system may lead to posterior circulation infarction at different locations in different age groups.

Effects of cilostazol on the progression and regression of symptomatic intracranial artery stenosis:it reduces the risk of ischemic stroke

OBJeCTIve：To assess the efifcacy and safety of cilostazol on the progression and regression of symptomatic intracranial artery stenosis. DATA ReTRIvAL： We searched the main databases for eligible trials including Medline （from 1966 to June 2014）, Embase （from 1980 to June 2014）, Cochrane Library （Issue 6, 2014）, Chinese National Knowledge Infrastructure （from 1995 to June 2014）, Current Controlled Trials （http：//controlled-trials.com）, Clinical Trials.gov （http：//clinicaltrials.gov）, and Chinese Clinical Trial Registry （http：//www.chictr.org）. All studies regarding prevention and treatment of symptomatic intracranial arterial stenosis by cilostazol were collected. The Mesh or text keywords were the En-glish words： “cilostazol, phosphodiesterase 3 inhibitor, atherosclerosis, and ischemic stroke.” No restrictions were put on publications or publication language. SeLeCTION CRITeRIA：Grade A or B randomized controlled trials were selected according to the quality of evaluation criteria from the Cochrane Collaboration, in which cilostazol and aspi-rin were used to evaluate the effects of cilostazol in the treatment of patients with symptomatic intracranial artery stenosis. The quality of study methodology was evaluated based on criteria de-scribed in Cochrane Reviewer’s Handbook 5.0.1. RevMan 5.2 software was used for data analysis. MAIN OUTCOMe MeASUReS： Clinical efifcacy and safety of cilostazol in stopping progression and promoting regression of symptomatic intracranial artery stenosis were measured by magnet-ic resonance angiography and transcranial Doppler. ReSULTS：Two randomized controlled trials with a total of 203 patients were included in this study. The results showed that while cilostazol was associated with a significantly reduced progression of intracranial artery stenosis （OR = 0.21, 95%CI： 0.09–0.47,P 〈 0.01）, it had no beneifcial effect on symptom regression （OR = 1.42, 95%CI： 0.80–2.51,P = 0.24）. During the follow-up period, although some adverse effects developed, including headache, gastrointestinal disturbance, and dizziness, incidences of bleeding were lower than in aspirin-treated patients. CONCLUSION：Cilostazol may prevent the progression of symptomatic intracranial artery ste-nosis, which could reduce the incidence of ischemic stroke.

Preparation of Thrombosis-targeted Lipid Microbubbles and Determination of Rabbit Carotid Artery Thrombosis by Microbubbles Ultrasonogaphy

A kind of thrombus-targeted lipid-coated microbubbles were prepared, and the target prop- erty of the microbubbles and the effects of different methods detecting thrombosis in vessels were ob- served. Phospholipid-coated microbubbles were prepared by membrane-hydration method. Throm- bus-targeted lipid-coated fluorocarbon microbubbles were labeled with specific fluorescence and then integrated to the thrombus in vivo and ex vivo through an avidin biotin system. The thrombus was im- mediately observed for the distribution and property of the thrombus-targeted microbubbles under the optical microscope, fluorescence microscope and transmission electron microscope. The carotid throm- bosis models were set up in rabbits, and the effects of different methods detecting thrombosis in vessels were observed. The diameter of the phospholipid-coated microbubbles was 0.8-2.5μm, and even reached nanoscale in some of them. The zeta electric potential was about -11 mV and the concentration was about 1.08×10μmL. Immunofluorescence of rapid frozen sections in vivo and ex vivo showed that massive targeted lipid-coated microbubbles flocked around fresh blood clots and some aggregated within them under the light and fluorescence microscope. The number of aggregated microbubbles ex vivo was greater than that observed in the experiment in vivo, and the fluorescence observed in the ex- periment ex vivo was stronger than that in the experiment in vivo. The same imaging was observed un- der the electron microscope. Models of carotid thrombosis in rabbits were established successfully. Ef- fects of detecting thrombosis by means of thrombosis-targeted microbubble ultrasonoraphy and Sono Vue ultrasonography in vessels were more satisfactory than those by Color Doplor Flow Imaging （CDFI）, ordinary microbubbles and Three Dimensions-time of flight MR angiography （3D-TOF-MRA） （P〈0.01）. Compared to ordinary microbubbles ultrasonography, thrombosis-targeted microbubbles ultrasonography had the advantages whenever in imaging quality or in imaging time. Thrombus-targeted phospholipid-coated microbubbles were prepared successfully by membrane-hydration method. They could aggregate rapidly in fresh blood clots and enter deep into the internal part of the thrombus both in vivo and ex vivo, and had the targeted property of strongly conjugating with the thrombus. Compared to other thrombosis detection methods, ultrasonography with thrombosis-targeted microbubbles has obvious advantages in detecting thrombosis in vessels, mainly in： non-invasiveness, safety, good image quality, accuracy, and longer imaging time.

DCAU-Net:dense convolutional attention U-Net for segmentation of intracranial aneurysm images

Segmentation of intracranial aneurysm images acquired using magnetic resonance angiography(MRA)is essential for medical auxiliary treatments,which can effectively prevent subarachnoid hemorrhages.This paper proposes an image segmentation model based on a dense convolutional attention U-Net,which fuses deep and rich semantic information with shallow-detail information for adaptive and accurate segmentation of MRA-acquired aneurysm images with large size differences.The U-Net model serves as a backbone,combining dense block and convolution block attention module(CBAM).The dense block is composed of a batch normalization layer,an randomly rectified linear unit activation function,and a convolutional layer,for mitigation of vanishing gradients,for multiplexing of aneurysm features,and for improving the network training efficiency.The CBAM is composed of a channel attention module and a spatial attention module,improving the segmentation performance of feature discrimination and enhancing the acquisition of key feature information.Owing to the large variation of aneurysm sizes,multi-scale fusion is performed during up-sampling,for adaptive segmentation of MRA-acquired aneurysm images.The model was tested on the MICCAI 2020 ADAM dataset,and its generalizability was validated on the clinical aneurysm dataset(aneurysm sizes:<3 mm,3–7 mm,and>7 mm)supplied by the Affiliated Hospital of Qingdao University.A good clinical application segmentation performance was demonstrated.

Acute Cerebral Infarction:A Case Report

This case report describes the presentation,diagnosis,and management of a 48-year-old man with acute cerebral infarction of the left fronto-parietal-superior temporal lobe.The patient presented to the local hospital with sudden onset of right limb weakness associated with right-sided deviation of the mouth and tongue,and slurred speech.The diagnosis of middle cerebral artery occlusion was made according to clinical symptoms and signs and some diagnostic tests including non-contrast computed tomography.Thrombolytic therapy with alteplase was given at the local hospital.The patient presented to the emergency department in the First Affiliated Hospital,Zhejiang University School of Medicine 8 hours after symptom onset for cerebrovascular stenting as recommended by the local hospital.The magnetic resonance angiography was performed and the M1 segment of middle cerebral artery stenosis was made as diagnosis.After acute management the patient was transferred to the neurology department for further management.This case highlights the critical importance of timely diagnosis,severity assessment,thrombolytic therapy,and intervention in ischemic stroke.Insights gained from this case contribute to the evolving understanding of cerebrovascular events.

Evaluating non-invasive medical imaging for diagnosis of carotid artery stenosis with ischemic cerebrovascular disease

Objectives To assess the value of non-invasive medical imaging for diagnosis of carotid artery stenosis and to study the relationship between carotid stenosis and brain infarction. Methods Thirty-one patients with a total of 62 carotid arteries were studied using Doppler ultrasound (DUS) and magnetic resonance angiography (MRA). Eleven of the 31 patients were studied using CT angiography (CTA). CT and MRI of the brain were also done in all patients. The imaging results in 5 patients were compared with those of digital subtraction angiography (DSA). Eight patients with severe stenosis received carotid endarterectomy. The comparisons between the imaging results and pathological data were conducted in 2 patients. Results Of the 62 carotid arteries, mild stenosis was seen in 11, moderate in 14, severe in 21, obstructed in 4 and normal in 12. In 25 patients with severe stenosis or occlusion of carotid arteries, there were a total of 35 focal or multifocal infarcts on the ipsilateral cerebral hemisphere, and 15 infarcts on the contrary side. Compared with the results of the operations, DUS correctly diagnosed 6 stenoses, while MRA identified 7 correctly and CTA 8. Agreement on location of stenosis as performed by endarterectomy, DUS, MRA and CTA occurred in all patients. Histologically, areas of calcification and fibrousness were related to high densities on CTA, strong echoes on DUS, and low signal intensities on MRA. Relatively large amounts of necrotic material and foam cells filled with lipolytic materials on the intimal surface of arteries were observed during pathologically, corresponding to low and iso-densities on CTA, low echoes on DUS, and inhomogeneous signal intensities on MRA. Conclusions A strong link exists between carotid stenosis and brain infarction. The combined use of DUS, MRA and CTA can improve diagnostic accuracy for the assessment of carotid artery stenosis, as well as assist in ascertaining the nature of the plaque.

Perimesencephalic Subarachnoid Hemorrhage in Pregnancy: A Case Report

Perimesencephalic subarachnoid hemorrhage (P-SAH) is a benign subset of subarachnoid hemorrhage. Only two cases of P-SAH during pregnancy have been reported in the literature. We describe a case of P-SAH detected at 29 weeks’ gestation, arose with severe bilateral frontal headache, neck rigidity, and vomiting. A diagnosis of P-SAH was confirmed on magnetic resonance angiography with no evidence of vascular malformation or bleeding sources and conservatively treated. Hemorrhage, vasospasm, and cerebellar edema observed on initial magnetic resonance angiography resolved after two months. The clinical course of P-SAH during pregnancy appears to be favorable. Our case shows for the first time in literature that magnetic resonance angiography is a valid diagnostic test for P-SAH during pregnancy that circumvents radiological risk associated with conventional imaging.